Loading arms that transfer flowing material in bulk from a storage container 15 (shown in phantom in dashed line) into a transport tank (not shown in FIG. 1) carried on a truck or rail car (not shown in FIG. 1) for transport are known. Such conventional loading arms include an articulating arm that is depicted in FIG. 1 and designated generally by the numeral 16. An articulating arm 16 can weigh five or six hundred pounds or more and include a plurality of connected hollow pipes that pivotally articulate in several ways in order to position the arm's outlet 17 over the hatch in the top of the transport tank (not shown in FIG. 1) that is being loaded with fluid (typically a liquid) or fluidized solid material. As schematically shown in FIG. 1, the loading arm 16 can be provided with a mechanism 18 (e.g., a counterbalance spring, a pneumatic cylinder or an hydraulic cylinder) to lower portions of the arm 16 into the transport tank (not shown in FIG. 1) or lift those portions of the arm 16 out of the transport tank.
As schematically shown in FIG. 1, the conventional loading arm 16 can be provided with a hatch plate 19 that is intended to prevent vapors from escaping to the atmosphere during the loading of the bulk material into the transport tank (not shown in FIG. 1). Moreover, though not shown in FIG. 1, such a hatch plate 19 also can be attached to the discharge end of a flexible hose that is used to carry the bulk material from storage into the transport tank (not shown in FIG. 1).
As shown in FIG. 1, a conventional hatch plate 19 can carry a level sensor 20 that projects partially above and partially beneath the hatch plate 19 and senses the level of the bulk material inside the transport tank (not shown in FIG. 1) so that the filling process can be halted before the bulk material overflows the top hatch of the transport tank. As shown in FIG. 1, a conventional hatch plate 19 can carry a vapor pipe 21 that projects partially above the hatch plate 19 and can be connected to a flexible vapor hose 22 that carries off vapor or dust that is given off by the bulk material being transported into the transport tank (not shown in FIG. 1) and allows the vapor or dust to be collected in an exhaust vessel 23 (shown in phantom in dashed line).
As shown in FIG. 1, an input product pipe 24 can extend beneath a conventional hatch plate 19 and project through the top hatch and into the transport tank (not shown in FIG. 1). As shown in FIG. 1, this input product pipe 24 can be provided with a telescoping extension tube 25 that can be selectively dropped down further into the transport tank (not shown in FIG. 1) in order to discharge the bulk material with less splash on the bottom of the transport tank. As shown in FIG. 1, this input product pipe 24 can be provided with one or more electrical ground cables 26 that prevent the buildup of static electricity during the process of filling the transport tank with bulk material.
As shown in FIG. 1, it is known to use a plurality of so-called “J” hooks 27 to secure such hatch plate 19 to the top hatch of a transport tank (not shown in FIG. 1) carried by rail car for example. Though not shown in FIG. 1, a plurality of bolts having one end pivotally connected to the hatch and the opposite end being threaded to receive a threaded nut can be received in slots formed in the peripheral edge of the hatch plate to secure same to the hatch. However, whether due to wear to the hatch or to the hatch plate 19, warping of the hatch plate 19 due to repeated temperature changes from weather or damage to one or both of them through repeated bumping during the process of aligning the arm's hatch plate 19 over the top hatch of the transport tank, gaps can develop between the hatch plate 19 and the top edge of the tank's hatch. Despite the use of such “J” hooks 27 (or bolt and nut fasteners), each such gap allows unwanted vapors or dust to pass between the top edge of the tank's hatch and the underside of the hatch plate 19 and thus escape to the atmosphere during the loading of the bulk material into the transport tank. Moreover, whether due to the operating limitations of the arm 16, uneven tracks beneath the rail car carrying the transport tank or a sloped grade beneath the truck carrying the transport tank, it is not always possible to get the pipe that supports the hatch plate 19 to address the hatch in the ideal alignment that is perpendicular to the plane of the top of the hatch. And the result of such misalignment is the presence of gaps between the top edge of the tank's hatch and the underside of the hatch plate 19 that allows unwanted vapors or dust escaping to the atmosphere during the loading of the bulk material into the transport tank.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate at least one presently preferred embodiment of the invention as well as some alternative embodiments. These drawings, together with the written description, serve to explain the principles of the invention but by no means are intended to be exhaustive of all of the possible manifestations of the invention.